X ্ͷ࠶ੜ֩ώϧϕϧτۭؒ (Reproducing Kernrl Hilbert Space, RKHS) ͱ ɺX ্ͷ͔ؔΒͳΔώϧϕϧτۭؒ H Ͱɺҙͷ x 2 X ʹରͯ͋͠Δؔ kx 2 H : X ! R ͕ଘࡏͯ͠ɺҎԼͷ࠶ੜੑΛຬͨ͢Λ͍͏ɻ hf; kxiH = f (x) (8f 2 H : X ! R) (3) ·ͣ x ͕༩͑ΒΕͯɺH ͷதͷҙͷؔ f ʹରͯ͠ɺͦΕͧΕͷ x ʹ্͍ͭͯهΛຬͨ ؔ͢ kx ͕ଘࡏ͢Δɺͱ͍͏Πϝʔδ ࠶ੜ֩ ্هͷఆٛͷ kx ʹରͯ͠ɺk (y; x) = kx (y) ʹΑͬͯఆ·ΔΧʔωϧ k : X ˆ X ! R Λ࠶ੜ֩ͱݺͿɻ 5